ML19134A186
| ML19134A186 | |
| Person / Time | |
|---|---|
| Issue date: | 05/20/2019 |
| From: | Jeffrey Poehler Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML19136A264 | List: |
| References | |
| Download: ML19134A186 (14) | |
Text
MRP-227, Rev. 1 Review and Applicant/Licensee Action Item Closure Jeff Poehler Sr. Materials Engineer Office of Nuclear Reactor Regulation Jeffrey.Poehler@nrc.gov (301) 415-8353 Materials Information Exchange Meeting May 21, 2019 Rockville, MD
MRP-227, Rev. 1 Review Status
- SE is publicly available (Ref. 1).
- SE contains one new applicant/licensee action item (A/LAI).
- Seven A/LAIs from MRP-227-A were generically resolved/eliminated.
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MRP-227, Rev. 1 Review
- 30 RAIs
- RAI responses received on October 16, 2017, January 30, 2018, and September 28, 2018, plus supplementary information on May 17, 2018.
- September 6, 2017
- October 5, 2017
- February 15, 2018
- April 23, 2018
- September 12, 2018 3 3
MRP-227, Rev. 1 Review - Major Issues - Core Barrel Girth Weld Coverage
- Due to emerging OE in 2018 with indications found in core barrel welds at one plant (RAI 29), EPRI proposed to examine 100% of the accessible weld length.
- For Westinghouse design, minimum coverage was set at 50% of total (accessible
+ inaccessible) due to limitations of some designs with neutron panels.
- For CE design, minimum coverage set at 75% (accessible+inaccessible),
consistent with MRP-227-A.
- Staff found revised coverage acceptable because welds will be examined to the maximum extent possible, and additional functionality and FMECA information supports lower achievable coverage for welds in neutron panel plants.
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Typical Westinghouse Design Core Barrel Typical Westinghouse RVI Arrangement Neutron Panel 5
MRP-227, Rev. 1 Review - Major Review Issues Baffle-Former Bolts
- Westinghouse baffle-former bolts (RAI 8) - related to consideration of recent (2016-2017) operating experience with higher-than-expected baffle-former bolt degradation in certain plants.
- Staff included an applicant/licensee action item to ensure plant-specific evaluations of subsequent examination intervals are submitted in a manner consistent with recommendation of staff assessment of EPRI BFB interim guidance (Ref. 3).
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MRP-227, Rev. 1 Review - Major Issues - Guide Cards
- 10 CFR 21 notification alerted the NRC to a potential significant safety hazard due to guide card wear in four plants that use ion nitrided rod cluster control assemblies (RCCAs) in conjunction with 17x17 A or 17x17 AS style guide tubes.
- EPRI revised note in MRP-227, Rev. 1 to reference WCAP-17451, Rev. 1 as modified by March 23, 2018 interim guidance for guide cards.
- NRC found aging management of guide cards acceptable because the interim guidance accelerates inspections for the plants in scope of the 10 CFR 21 notification.
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Guide Card Location and Configuration, Westinghouse RVI 8
Applicant/Licensee Action Item Closure
- The final SE of MRP-227-A contained eight applicant/licensee action items (A/LAI) that must be addressed by applicants or licensees implementing the topical report.
- Initially, lack of guidance on how to respond to some A/LAIs.
- A/LAIs 1,2,6, and 7 required significant effort by applicants or licensees.
- Both NRC and industry had a desire to minimize A/LAIs in topical report SEs.
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Applicant/Licensee Action Item Closure
- A/LAI 1 - Plant-specific applicability
- Not needed because adequate guidance in Section 2.4 and Appendix B of MRP-227, Rev. 1
- A/LAI 2 - Plant-specific components
- Adequate guidance in Section 2.4.
- A/LAI 7 - Plant-specific evaluation of CASS
- Not needed because functionality of the CASS components established by several generic technical reports reviewed by NRC.
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A/LAIs 3, 4, 5, 6, and 8
- These action items:
- Have been addressed by licensees already in plant-specific RVI Inspection Program submittals; or
- Have been determined to have low safety significance by the staff.
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SE Conclusions
- MRP-227, Revision 1, as modified by the SE, provides an acceptable means for managing aging of PWR reactor vessel internals.
- One A/LAI must be addressed related to submittal of plant-specific evaluations for baffle-former bolt inspection intervals (if applicable).
- MRP-227, Rev. 1 provides an acceptable starting point for a gap analysis for subsequent license renewal, in accordance with XI.M16A of NUREG-2191 (GALL-SLR) and NUREG-2192 (SRP-SLR) Section 3.1.2.2.9.
- An exception to GALL-SLR must be identified in such cases, until GALL-SLR and SRP-SLR are updated to reference MRP-227, Rev. 1-A.
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SLR Status
- NRC staff have participated in several public meetings with EPRI-MRP to discuss some of the technical work supporting the development of MRP-227, Rev. 2, the PWR Internals Inspection and Evaluation Guidance applicable to subsequent license renewal (80 years).
- February 13-14, 2018 (Ref. 4)
- MRP-175, Rev. 1 - EPRI - Materials Reliability Program: PWR Internals Material Aging Degradation Mechanism Screening and Threshold Values
- MRP-211, Rev. 1 - EPRI - Materials Reliability Program: PWR Internals Age-Related Material Properties, Degradation Mechanisms, Models, and Basis Data-State of Knowledge
- May 1, 2019 (Ref. 5)
- Materials Reliability Program: Screening, Categorization, and Ranking of Reactor Internals Components for Westinghouse and Combustion Engineering PWR Design (MRP-191, Revision 2)
- Materials Reliability Program: Inspection Standard for Pressurized Water Reactor Internals-2018 Update (MRP-228, Rev. 3).
- These interactions have been extremely helpful to the staff.
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References
- 1. Final Safety Evaluation For Electric Power Research Institute Topical Report MRP-227, Revision 1, Materials Reliability Program: Pressurized Water Reactor Internals Inspection And Evaluations Guideline April 25, 2019 (ML19081A001)
- 2. Final Safety Evaluation Of Action Items 1 And 7 From Topical Report MRP-227-A, Materials Reliability Program: Pressurized Water Reactor Internals Inspection And Evaluations Guideline, January 29, 2018 (ML18016A008)
November 20, 2017 (ML17310A861)
- 4. February 13, 2018 - February, 15, 2018 Meeting on MRP Reports. (ADAMS Accession No. ML18025B386)
- 5. May 1, 2019 Meeting on MRP-191, Rev 2 and MRP-228, Rev 3 (ADAMS Accession No. ML19094A017) 14 14